Anathema is a word that fell from the temple shelf. In classical Greek an anathema was a thing set up: the dedicated tripod, the votive shield, the offering placed on high in a sanctuary. The Septuagint used the cognate to translate the Hebrew herem, that which is devoted, irrevocably handed over to God, and since what was devoted was often devoted to destruction, the word's luminous and dark senses fused: set apart for God, and therefore removed from human use, and therefore, when applied to a person, accursed. Paul writes the dark sense fluently, wishing himself anathema for his brethren's sake, and pronouncing it on any who preach another gospel, and Christian usage followed him. From the fourth century the councils made it a formula: doctrinal canons closed with ei tis, anathema esto, if anyone says thus, let him be anathema, so that the church's definitions advanced behind a hedge of enumerated condemnations, Nicaea against the Arian formulas, Chalcedon's christological boundaries, Trent's hundred-plus canons against the Reformers.
Later Latin canon law distinguished anathema as excommunication delivered with full solemnity, bell, book and candle in the popular memory. The trajectory, from gift to curse, is not an irony but a logic: both senses mean handed over wholly, taken out of ordinary circulation, and the word's history is a reminder that the sacred is the category of the set-apart, whichever direction the setting runs.